This invention relates generally to air compressors and more particularly to gas turbine powered oil-free air compressors.
A typical industrial air compression system is shown in FIG. 1. A prime mover 10, which can be an electric motor or an internal combustion piston engine, is connected by a gear coupling 12 to a compressor 20. The compressor 20, typically a multi-stage intercooled compressor, can be a piston compressor, screw compressor or centrifugal compressor. Inlet air 22 is provided to the compressor 20 though an inlet air filter. After being compressed, the compressed air is normally cooled in an aftercooler 25. The cooled compressed air is then delivered to an air receiver or storage tank 50 from which the compressed air flows into an air distribution system 52.
When additional drying of the compressed air is required, the compressed air is processed through a dryer system 30. FIG. 1 shows a typical two tank desiccant dryer system. The dryer system 30 consists of two tanks 34a, 34b and associated valving, one system designated "a" and the other system designated "b" (Open valves are shown as "O" and closed valves are shown as "C"). As shown in FIG. 1, the "a" system is being regenerated and the "b" system is in service. Supply air inlet valves 36a, 36b direct the compressed air to the in-service tank 34a, 34b where a moisture absorbing desiccant absorbs moisture from the cooled compressed air. Supply air outlet valves 38a, 38b, direct the discharge of the in-service tank to the air receiver 50. Regeneration air inlet valves 37a, 37b direct either heated air from an auxiliary burner 32 or uncooled compressed air diverted from the compressor output prior to the aftercooler 25. As a result of exposure to the higher temperature air, the previously absorbed moisture is released from the desiccant into the higher temperature air. The regeneration air including the removed moisture is directed by regeneration air outlet valves 39a, 39b to a regeneration dump air line 40. This regeneration air is either released to a sump or to a vent.
The dumping of the regeneration air leads to a loss of the energy of compression in the compressed air and to the loss of the energy added by the auxiliary burner 32 (if used). The dumping of the regeneration air can cause a large pressure drop across the desiccant bed 34a, 34b being regenerated. Frequently, the pressure drop from the inlet to the outlet of the desiccant bed 34a, 34b is large enough to damage the desiccant bed.
The foregoing illustrates limitations known to exist in present industrial air compressor systems. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.